feat(simkl): add comprehensive error handling

SimklFunctions.go:
- Update SimklHelper to return (json.RawMessage, error)
- Add status code validation (200-299 range)
- Update SimklGetUserWatchlist to return (SimklWatchListType, error)
- Update SimklSyncEpisodes to return (SimklAnime, error)
- Update SimklSyncRating to return (SimklAnime, error)
- Update SimklSyncStatus to return (SimklAnime, error)
- Update SimklSearch to return (SimklAnime, error)
- Update SimklSyncRemove to return (bool, error)
- Add proper error wrapping for all failure scenarios

SimklUserFunctions.go:
- Replace log.Fatalf with log.Printf in server error handling (line 119)
- Replace log.Fatal with log.Printf in JSON marshaling (line 141)

All Simkl API calls now properly propagate errors to frontend.

SimklFunctions.go

@@ -14,16 +14,24 @@ import (
 
 var SimklWatchList SimklWatchListType
 
-func SimklHelper(method string, url string, body interface{}) json.RawMessage {
+func SimklHelper(method string, url string, body interface{}) (json.RawMessage, error) {
-	reader, _ := json.Marshal(body)
+	reader, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal body: %w", err)
+	}
+
 	var req *http.Request
 
 	client := &http.Client{}
 
 	if body != nil {
-		req, _ = http.NewRequest(method, url, bytes.NewBuffer(reader))
+		req, err = http.NewRequest(method, url, bytes.NewBuffer(reader))
 	} else {
-		req, _ = http.NewRequest(method, url, nil)
+		req, err = http.NewRequest(method, url, nil)
+	}
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
 	req.Header.Add("Content-Type", "application/json")
@@ -32,41 +40,45 @@ func SimklHelper(method string, url string, body interface{}) json.RawMessage {
 
 	resp, err := client.Do(req)
 	if err != nil {
-		fmt.Println("Errored when sending request to the server")
+		return nil, fmt.Errorf("network error: %w", err)
-		message, _ := json.Marshal(struct {
-			Message string `json:"message"`
-		}{
-			Message: "Errored when sending request to the server" + err.Error(),
-		})
-
-		return message
 	}
 
 	defer resp.Body.Close()
-	respBody, _ := io.ReadAll(resp.Body)
+	respBody, err := io.ReadAll(resp.Body)
 
-	return respBody
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return respBody, fmt.Errorf("API returned status: %d", resp.StatusCode)
+	}
+	return respBody, nil
 }
 
-func (a *App) SimklGetUserWatchlist() SimklWatchListType {
+func (a *App) SimklGetUserWatchlist() (SimklWatchListType, error) {
 	method := "GET"
 	url := "https://api.simkl.com/sync/all-items/anime"
 
-	respBody := SimklHelper(method, url, nil)
+	respBody, err := SimklHelper(method, url, nil)
+
+	if err != nil {
+		return SimklWatchListType{}, fmt.Errorf("failed to get Simkl watchlist: %w", err)
+	}
 
 	var errCheck struct {
 		Error   string `json:"error"`
 		Message string `json:"message"`
 	}
 
-	err := json.Unmarshal(respBody, &errCheck)
+	err = json.Unmarshal(respBody, &errCheck)
 	if err != nil {
 		log.Printf("Failed at unmarshal, %s\n", err)
+		return SimklWatchListType{}, fmt.Errorf("failed to parse error response: %w", err)
 	}
 
 	if errCheck.Error != "" {
 		a.LogoutSimkl()
-		return SimklWatchListType{}
+		return SimklWatchListType{}, fmt.Errorf("Simkl API error: %s", errCheck.Message)
 	}
 
 	var watchlist SimklWatchListType
@@ -74,14 +86,15 @@ func (a *App) SimklGetUserWatchlist() SimklWatchListType {
 	err = json.Unmarshal(respBody, &watchlist)
 	if err != nil {
 		log.Printf("Failed at unmarshal, %s\n", err)
+		return SimklWatchListType{}, fmt.Errorf("failed to parse watchlist: %w", err)
 	}
 
 	SimklWatchList = watchlist
 
-	return watchlist
+	return watchlist, nil
 }
 
-func (a *App) SimklSyncEpisodes(anime SimklAnime, progress int) SimklAnime {
+func (a *App) SimklSyncEpisodes(anime SimklAnime, progress int) (SimklAnime, error) {
 	var episodes []Episode
 	var url string
 	var shows []SimklPostShow
@@ -112,13 +125,19 @@ func (a *App) SimklSyncEpisodes(anime SimklAnime, progress int) SimklAnime {
 
 	simklSync := SimklSyncHistoryType{shows}
 
-	respBody := SimklHelper("POST", url, simklSync)
+	respBody, err := SimklHelper("POST", url, simklSync)
+
+	if err != nil {
+		log.Printf("Failed to sync episodes: %s\n", err)
+		return anime, fmt.Errorf("failed to sync episodes: %w", err)
+	}
 
 	var success interface{}
 
-	err := json.Unmarshal(respBody, &success)
+	err = json.Unmarshal(respBody, &success)
 	if err != nil {
 		log.Printf("Failed at unmarshal, %s\n", err)
+		return anime, fmt.Errorf("failed to parse response: %w", err)
 	}
 
 	for i, simklAnime := range SimklWatchList.Anime {
@@ -131,10 +150,10 @@ func (a *App) SimklSyncEpisodes(anime SimklAnime, progress int) SimklAnime {
 
 	WatchListUpdate(anime)
 
-	return anime
+	return anime, nil
 }
 
-func (a *App) SimklSyncRating(anime SimklAnime, rating int) SimklAnime {
+func (a *App) SimklSyncRating(anime SimklAnime, rating int) (SimklAnime, error) {
 	var url string
 	showWithRating := ShowWithRating{
 		Title: anime.Show.Title,
@@ -169,13 +188,17 @@ func (a *App) SimklSyncRating(anime SimklAnime, rating int) SimklAnime {
 		Shows []interface{} `json:"shows" ts_type:"shows"`
 	}{shows}
 
-	respBody := SimklHelper("POST", url, simklSync)
+	respBody, err := SimklHelper("POST", url, simklSync)
-
+	if err != nil {
+		log.Printf("Failed to sync rating: %s\n", err)
+		return anime, fmt.Errorf("failed to sync rating: %w", err)
+	}
 	var success interface{}
 
-	err := json.Unmarshal(respBody, &success)
+	err = json.Unmarshal(respBody, &success)
 	if err != nil {
 		log.Printf("Failed at unmarshal, %s\n", err)
+		return anime, fmt.Errorf("failed to parse response: %w", err)
 	}
 
 	for i, simklAnime := range SimklWatchList.Anime {
@@ -188,10 +211,10 @@ func (a *App) SimklSyncRating(anime SimklAnime, rating int) SimklAnime {
 
 	WatchListUpdate(anime)
 
-	return anime
+	return anime, nil
 }
 
-func (a *App) SimklSyncStatus(anime SimklAnime, status string) SimklAnime {
+func (a *App) SimklSyncStatus(anime SimklAnime, status string) (SimklAnime, error) {
 	url := "https://api.simkl.com/sync/add-to-list"
 	show := SimklShowStatus{
 		Title: anime.Show.Title,
@@ -211,13 +234,17 @@ func (a *App) SimklSyncStatus(anime SimklAnime, status string) SimklAnime {
 		Shows []SimklShowStatus `json:"shows" ts_type:"shows"`
 	}{shows}
 
-	respBody := SimklHelper("POST", url, simklSync)
+	respBody, err := SimklHelper("POST", url, simklSync)
-
+	if err != nil {
+		log.Printf("Failed to sync status: %s\n", err)
+		return anime, fmt.Errorf("failed to sync status: %w", err)
+	}
 	var success interface{}
 
-	err := json.Unmarshal(respBody, &success)
+	err = json.Unmarshal(respBody, &success)
 	if err != nil {
 		log.Printf("Failed at unmarshal, %s\n", err)
+		return anime, fmt.Errorf("failed to parse response: %w", err)
 	}
 
 	for i, simklAnime := range SimklWatchList.Anime {
@@ -230,15 +257,20 @@ func (a *App) SimklSyncStatus(anime SimklAnime, status string) SimklAnime {
 
 	WatchListUpdate(anime)
 
-	return anime
+	return anime, nil
 }
 
-func (a *App) SimklSearch(aniListAnime MediaList) SimklAnime {
+func (a *App) SimklSearch(aniListAnime MediaList) (SimklAnime, error) {
 	var result SimklAnime
 
 	if reflect.DeepEqual(SimklWatchList, SimklWatchListType{}) {
 		fmt.Println("Watchlist empty. Calling...")
-		SimklWatchList = a.SimklGetUserWatchlist()
+		watchlist, err := a.SimklGetUserWatchlist()
+		if err != nil {
+			log.Printf("Failed to get watchlist: %s\n", err)
+			return result, fmt.Errorf("failed to load watchlist for search: %w", err)
+		}
+		SimklWatchList = watchlist
 	}
 
 	for _, anime := range SimklWatchList.Anime {
@@ -255,22 +287,30 @@ func (a *App) SimklSearch(aniListAnime MediaList) SimklAnime {
 		var anime SimklSearchType
 		url := "https://api.simkl.com/search/id?anilist=" + strconv.Itoa(aniListAnime.Media.ID)
 
-		respBody := SimklHelper("GET", url, nil)
+		respBody, err := SimklHelper("GET", url, nil)
-
+		if err != nil {
-		err := json.Unmarshal(respBody, &anime)
+			log.Printf("Failed to search Simkl: %s\n", err)
+			return result, fmt.Errorf("failed to search Simkl by AniList ID: %w", err)
+		}
+		err = json.Unmarshal(respBody, &anime)
 
 		if len(anime) == 0 {
 			url = "https://api.simkl.com/search/id?mal=" + strconv.Itoa(aniListAnime.Media.IDMal)
-			respBody = SimklHelper("GET", url, nil)
+			respBody, err = SimklHelper("GET", url, nil)
+			if err != nil {
+				log.Printf("Failed to search Simkl by MAL ID: %s\n", err)
+				return result, fmt.Errorf("failed to search by MAL ID: %w", err)
+			}
 			err = json.Unmarshal(respBody, &anime)
 		}
 
 		if err != nil {
 			log.Printf("Failed at unmarshal, %s\n", err)
+			return result, fmt.Errorf("failed to parse search results: %w", err)
 		}
 
 		if len(anime) == 0 {
-			return result
+			return result, nil
 		}
 
 		for _, watchListAnime := range SimklWatchList.Anime {
@@ -288,10 +328,10 @@ func (a *App) SimklSearch(aniListAnime MediaList) SimklAnime {
 		}
 	}
 
-	return result
+	return result, nil
 }
 
-func (a *App) SimklSyncRemove(anime SimklAnime) bool {
+func (a *App) SimklSyncRemove(anime SimklAnime) (bool, error) {
 	url := "https://api.simkl.com/sync/history/remove"
 	var showArray []SimklShowStatus
 
@@ -312,25 +352,28 @@ func (a *App) SimklSyncRemove(anime SimklAnime) bool {
 		Shows: showArray,
 	}
 
-	respBody := SimklHelper("POST", url, show)
+	respBody, err := SimklHelper("POST", url, show)
 
+	if err != nil {
+		log.Printf("Failed to sync remove: %s\n", err)
+		return false, fmt.Errorf("failed to sync remove: %w", err)
+	}
 	var success SimklDeleteType
-
+	err = json.Unmarshal(respBody, &success)
-	err := json.Unmarshal(respBody, &success)
 	if err != nil {
 		log.Printf("Failed at unmarshal, %s\n", err)
+		return false, fmt.Errorf("failed to parse response: %w", err)
 	}
-
 	if success.Deleted.Shows >= 1 {
 		for i, simklAnime := range SimklWatchList.Anime {
 			if simklAnime.Show.Ids.Simkl == anime.Show.Ids.Simkl {
 				SimklWatchList.Anime = slices.Delete(SimklWatchList.Anime, i, i+1)
 			}
 		}
-		return true
+		return true, nil
-	} else {
-		return false
 	}
+
+	return false, fmt.Errorf("no shows were deleted")
 }
 
 func WatchListUpdate(anime SimklAnime) {

SimklUserFunctions.go

@@ -116,7 +116,7 @@ func (a *App) handleSimklCallback(wg *sync.WaitGroup) {
 	go func() {
 		defer wg.Done()
 		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
-			log.Fatalf("listen: %s\n", err)
+			log.Printf("Server error: %s\n", err)
 		}
 		fmt.Println("Shutting down...")
 	}()
@@ -138,7 +138,8 @@ func getSimklAuthorizationToken(content string) SimklJWT {
 	}
 	jsonData, err := json.Marshal(data)
 	if err != nil {
-		log.Fatal(err)
+		log.Printf("Failed to marshal data: %s\n", err)
+		return SimklJWT{}
 	}
 
 	response, err := http.NewRequest("POST", "https://api.simkl.com/oauth/token", bytes.NewBuffer(jsonData))